CONCLUSION

Table 6.1. Maximal real s. s.v. obtained with the computational methods.

complex /г UB

UB by J.

mixed UB

UB by ZD

LB by D.

poly. LB

PI

0.13

0.13

0.13

0.13

0.13

*

P2

0.31

0.28

0.25

0.25

0.24

*

P4

0.32

*

0.23

*

*

0.18

P5

1.06

*

0.65

*

*

0.58

The #oo missile autopilot was proved to exhibit good robust stability and performance properties in the presence of uncertainties in the aero­dynamic model. The robustness margin obtained when analyzing the robust stability property inside the left half plane is very good, as well as the robustness margin corresponding to the robust stability property inside a truncated sector. The results obtained when defining the per­formance in the frequency domain (subsection 1.3) appear disappointing. However, as indicated in chapter 9, the poor quality of these results is due to the use of classical p tools: it will come out that the results ob­tained when defining the performance in the frequency domain and when using skewed p tools appear very close to those obtained when defining the performance through a truncated sector.

Concerning the methods, see first the table above for a comparison of the estimates of the robustness margins, obtained with the different computational methods. In the case of the missile problem, whose di­mension is not too large, the best results are obtained by combining the upper bound by Zadeh and Desoer and the lower bound by Dailey. The mixed /j upper bound by Fan et al also gives good results.

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